The present invention relates to a control apparatus for a vehicle equipped with continuously-variable transmission, adapted to perform a vehicle-stop LOW shift control that shifts a pulley ratio toward LOW side at the time of vehicle stop.
In the case of a vehicle equipped with belt-type continuously-variable transmission, there is a possibility that the vehicle stops under a state where the pulley ratio has not yet returned to its LOWEST state in dependence upon driver's manipulations, a road-surface state and the like, for example, when a pattern of running (moving)→deceleration→stop→restart has been repeated. After the vehicle has stopped under a pulley-ratio state other than the LOWEST state, if trying to restart the vehicle under this pulley-ratio state, a torque sufficient to start to move the vehicle is not secured. Hence, an acceleration performance for vehicle restart is inferior.
U.S. Patent Application Publication No. 2002-072441 (corresponding to Japanese Patent Application Publication No. 2002-181180) discloses a previously-proposed control apparatus for a vehicle equipped with continuously-variable transmission. In this technique, a vehicle-stop LOW shift control is performed which forcibly shifts the pulley ratio toward LOW side when the vehicle stops under a pulley-ratio state departed from a LOWEST region, in order to obtain a LOWEST-side pulley-ratio state before restarting the vehicle from the stopped state and also in order to prevent a slip between a pulley and a belt.
The above previously-proposed control apparatus defines the following conditions (a) to (c) as a start condition (criteria) for the vehicle-stop LOW shift control.
(a) The pulley ratio of belt-type continuously-variable transmitting mechanism is not in the LOWEST state.
(b) A rotational element of belt-type continuously-variable transmitting mechanism is in a stopped state.
(c) The belt-type continuously-variable transmitting mechanism is not in a power-transferring state.
That is, the vehicle-stop LOW shift control which forcibly shifts the pulley ratio of the belt-type continuously-variable transmitting mechanism toward LOW side is started when all of three conditions of the pulley-ratio condition (a), the rotational-element-stop condition (b) and the neutral condition (c) are satisfied.